This Application is a 371 of PCT/FR99/01260 filed May 28, 1999, which claims priority to French Application 98/06821 filed May 29, 1998.
The present invention relates in general terms to the use of saponins or sapogenols in cosmetology and for the manufacture of pharmaceutical compositions for treating the skin in order to increase the amount of collagen IV in the dermo-epidermal junction.
It further relates to novel cosmetic or pharmaceutical compositions which promote an increase in the amount of collagen IV in the dermo-epidermal junction, and to a method of cosmetic treatment using a saponin or a sapogenol.
The dermo-epidermal junction is known to be a complex structure which assures the cohesion and exchanges between the dermis and the epidermis which are essential for the skin to function properly.
It is further known that type IV collagen, also called collagen IV, is a major constituent of the dermo-epidermal junction, which is involved especially in maintaining a functional interface between the dermis and the epidermis.
The optimum physiological state of the dermo-epidermal junction depends on there being a sufficient amount of collagen IV in this dermo-epidermal junction.
Therefore, to maintain or restore the physiological state of the dermo-epidermal junction, it is desirable to have a means of increasing the amount of collagen IV therein.
It has been discovered that triterpenic saponins and sapogenols, preferably of type A or type B and especially those which are cosmetically or pharmaceutically acceptable, are particularly appropriate as agents for increasing the amount of collagen IV in the dermo-epidermal junction; it is this discovery which constitutes the basis of the present invention.
Thus, according to a first feature, the present patent application aims to cover the use of at least one cosmetically acceptable saponin or sapogenol of triterpenic character, particularly a saponin or sapogenol extracted from a plant, preferably from soya or a plant of the Medicago type, or of a plant extract rich in such compounds, as a cosmetic agent for increasing the amount of collagen IV in the dermo-epidermal junction.
As well as the cosmetic field, the invention is also applicable in the pharmaceutical field, especially the dermatological field.
Thus, according to a second feature, the present patent application aims to cover the use of at least one pharmaceutically acceptable saponin or sapogenol of triterpenic character, particularly a saponin or sapogenol extracted from a plant, preferably from soya or a plant of the Medicago type, or of a plant extract rich in such compounds, for the manufacture of a pharmaceutical composition, especially dermatological composition, for treating pathological conditions associated with a deficiency of the dermo-epidermal junction resulting from an insufficient amount of collagen IV.
A very large number of saponins and sapogenols of triterpenic character are found to be appropriate within the framework of the use according to the present invention, in the cosmetic or pharmaceutical field.
These compounds, which will have to be cosmetically or pharmaceutically acceptable within the framework of a cosmetic or pharmaceutical use, will advantageously be extracted from plants. They could also be obtained by chemical synthesis, as is easily comprehensible and known to those skilled in the art.
In particular, it will be possible to use saponins extracted from plants, preferably those extracted from Glycine max (soya), Phaseolus vulgaris, Phaseolus aureus, Phaseolus lunatus, Vicia faba, Lens culinaris, Cicer arietum, Vigna angularis, Vigna mungo, Oxytropis ochrocephala, Oxytropis glabra, Pisum sativum, Sophora favescens, Asparalus membranaceus, Crotalaria albida, Arachis hypogea, Galega officinalis, Wistaria brachybotrys and Trifolium repens, or those extracted from plants of the Medicago type, particularly Medicago alfalfa and Medicago sativa, which is often called xe2x80x9calfalfaxe2x80x9d.
According to a third feature, the present patent application aims to cover the use of at least one saponin or sapogenol extracted from a plant rich in such compounds and selected from Glycine max (soya), Phaseolus vulgaris, Phaseolus aureus, Phaseolus lunatus, Vicia faba, Lens culinaris, Cicer arietum, Vigna angularis, Vigna mungo, Oxytropis ochrocephala, Oxytropis glabra, Pisum sativum, Sophora favescens, Asparalus membranaceus, Crotalaria albida, Arachis hypogea, Galega officinalis, Wistaria brachybotrys and Trifolium repens, or a plant of the Medicago type, particularly Medicago alfalfa and Medicago sativa, or xe2x80x9calfalfaxe2x80x9d, as a cosmetic agent for increasing the amount of collagen IV in the dermo-epidermal junction.
According to a fourth feature, the present invention aims to cover the use of at least one saponin or sapogenol extracted from a plant rich in such compounds and selected from Glycine max (soya), Phaseolus vulgaris, Phaseolus aureus, Phaseolus lunatus, Vicia faba, Lens culinaris, Cicer arietum, Vigna angularis, Vigna mungo, Oxytropis ochrocephala, Oxytropis glabra, Pisum sativum, Sophora favescens, Asparalus membranaceus, Crotalaria albida, Arachis hypogea, Galega officinalis, Wistaria brachybotrys and Trifolium repens, or a plant of the Medicago type, particularly Medicago alfalfa and Medicago sativa, or xe2x80x9calfalfaxe2x80x9d, for the manufacture of a pharmaceutical composition, especially dermatological composition, for treating pathological conditions associated with a deficiency of the dermo-epidermal junction resulting from an insufficient amount of collagen IV.
Soya and plants of the Medicago type, such as Medicago sativa, are particularly appropriate plants for providing saponins or sapogenols which can be used within the framework of the invention, since said compounds are of the triterpenic type and, in particular, of type A or type B.
These saponins or sapogenols of triterpenic character will advantageously comprise type A or type B triterpenic soya saponins or soya sapogenols and may be extracted in particular from a plant of the Medicago type, such as Medicago alfalfa and Medicago sativa. 
These type A or type B triterpenic soya saponins or soya sapogenols are well known in the literature (cf. on the one hand the article by Georges Massiot, Catherine Lavaud, Dominique Guillaume and Louisette Le Men-Olivier in J. Agric. Food Chem. (1988), 36, pages 902-909, and on the other hand the book entitled xe2x80x9cSaponinsxe2x80x9d by Hostettman K. and Marston A. (1995), published by Cambridge University Press, particularly Appendix 2, references 446 to 460 and 517 to 519. They have the following chemical formulae:
type A soya sapogenol 
type B soya sapogenol 
Sapogenols do not contain a sugar substituent, so they are generally called aglycones. On the other hand, they can be substituted by sugars or sugar chains and are then called soya saponins, which can thus be of type A or type B.
The following may be mentioned as examples:
The above-mentioned triterpenic saponins or sapogenols can be extracted from any part of the plant, but will preferably be extracted from the roots in the case of Medicago and from the seeds in the case of soya.
The extraction conditions are well known to those skilled in the art, who may refer e.g. to the document WO 92/09262, which is incorporated here by way of reference.
Within the framework of the use according to the present invention, the proportion of saponin(s) or sapogenol(s), or of plant extract containing them, is advantageously between 0.001% and 5% by weight, preferably between 0.01 and 2% by weight, based on the total weight of the final cosmetic or pharmaceutical composition.
It has also been discovered, totally unexpectedly, that the beneficial effect of saponins and sapogenols, irrespective of their character, i.e. even if said saponin or said sapogenol is not of triterpenic character, although it is preferable to use a saponin or sapogenol of triterpenic character, preferably of type A or type B, can be substantially increased if these compounds are used in association with an ecdysteroid or an acetylated ecdysteroid derivative such as, in particular, xcex2-ecdysone or ecdysterone.
Ecdysteroids, and particularly ecdysterone, are well-known natural substances found especially in insects and in certain plants such as Polypodium vulgare and Cyanotis arachnoidea. 
Within the framework of the use of a saponin or sapogenol in association with an ecdysteroid, these compounds will be used in a weight ratio preferably of between 1:10 and 10:1 and particularly preferably of 1:1.
The saponins or sapogenols can also be used in association with another active substance selected e.g. from the group consisting of madecassic acid, asiatic acid, madecassoside, asiaticoside, xcex1-1-proteinase inhibitor, collagenase inhibitors such as retinoic acid, elastase inhibitors, lysine, proline, 2-oxoglutarate, ginsenoside R0, vitamin D and derivatives thereof, other vitamins, particularly vitamin A, B or E, xanthines, tyrosine or derivatives thereof, for example glucose tyrosinate or malyltyrosine, quinine or derivatives thereof, rubefacients such as methyl nicotinate, keratin hydrolyzates, trace elements such as zinc, selenium or copper, 5-xcex1-reductase inhibitors such as progesterone or cyproterone acetate, minoxidil, azelaic acid and derivatives thereof, 1,4-methyl-4-azasteroid, particularly 17xcex2-N,N-diethylcarbamoyl-4-methyl-4-aza-5-xcex1-androstan-3-one, or an extract of Serenoa repens. 
In this case the concentration of this (these) other active substance(s) is between 0.0001% and 5% by weight, based on the weight of the final composition.
These substances, including the saponins or sapogenols, can optionally be at least partially incorporated into hydrated lipidic lamellar phases or liposome-type vesicles.
According to a fifth feature, the present patent application aims to cover novel cosmetic or pharmaceutical compositions which promote an increase in the amount of collagen IV in the dermo-epidermal junction.
These compositions are essentially characterized in that they contain an effective amount of at least one saponin or sapogenol, irrespective of its character, can be of non-triterpenic character, but preferably at least one saponin or sapogenol of triterpenic character, particularly preferably of type A or type B, in association with at least one ecdysteroid, particularly xcex2-ecdysone or ecdysterone.
In this case the above-mentioned saponin or sapogenol and the above-mentioned ecdysteroid are associated in a weight ratio of between 1:10 and 10:1 and preferably of 1:1.
According to a sixth feature, the present patent application aims to cover a method of cosmetic treatment in which an effective amount of at least one saponin or at least one sapogenol as defined above, optionally in association with one or more other active substances such as those mentioned above, and/or in association with an ecdysteroid, particularly ecdysterone, is administered topically to a person in need thereof.